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nature—is increased by displacing the cold air remaining in the interstices
of the material; otherwise the interchange of air and steam
particles, and of temperature, would take place comparatively slowly.
A large feather bed should be in the apparatus at least an hour, and
the steam relaxed three or four times. In experiments tried by
me this method answered most satisfactorily, the temperature in the
interior of a featherbed reaching 212° F. on one occasion, and 225°
F. on another. The time given in the old apparatus was three hours,
and its heating powers totally inadequate to penetrate beds. Flock
beds require to be under steam for about half an hour. Blankets,
woollen articles, and garments must not be exposed to the steam for
more than fifteen minutes, the pressure being relaxed once, as with
such articles there is the danger of felting together and loss of elasticity
and fluffiness. This elasticity depends upon the presence of
the natural grease (suint) of the wool. Leather and fur articles must
not be subjected to steam in the chamber, but to that in the jacket
for an hour or more. The working temperature of the jacket is 268°
F., and that of the chamber 260° F. The contagia of the ordinary
infectious diseases of mankind are not likely to withstand an exposure
of an hour to dry heat of 220° F., or one of five minutes to boiling
water or steam of 212° F.
Increased ventilation was given to the disinfecting house as it became
exceedingly hot, and the apparatus, with the boiler, was coated with
a non-conducting material to prevent the loss of heat, and to lessen
the expense for fuel. A condenser has also been erected to obviate
the steam from being discharged into the atmosphere, and taps have
been fixed at all junctions and bends of pipes to run any water away
before leaving off work, so that freezing, with its concomitant
dangers, might be prevented during the prevalence of frost.
The following figures give the number of premises disinfected, and
the number of times the Board's apparatus was used for the two
parishes, some thousands of articles being disinfected.